This invention relates to the field of mobile robots and more particularly to a cooperative search controller test system using multiple mobile robots.
The use of multiple robots is particularly applicable in surveillance and inspection, in searching, in following and tagging, in locating and identifying targets, and in other applications which potentially remove humans from tedious or potentially hazardous activities. Search controllers are used to control the robots to search for an objective. Search controllers also are used to control software agents to search for an objective in computer cyberspace.
The search controllers can be most effective and efficient when large numbers of robots or agents are used. Multiple robots controlled to cooperatively achieve a search objective have the potential to be more effective than a collection of independent robots, providing the robots"" searches minimize overlap and the robots do not collide. Multiple robots in a collective can collect and share information to enhance each robot""s strategy to achieve the objective. Independent and distributed sensing and sharing of information among multiple autonomous or semi-autonomous cooperating robots as well as cooperative control for each robot can improve the search strategy to achieve the objective without sacrificing efficiency or imposing an undue communication or processing burden.
Mobile Robots
Different mobile robot platforms exist, spanning a wide range of costs and capabilities, from robots with electronic packages for specialized operations to inexpensive remote control cars and robots for educational applications. Remote control toys generally are operated as single units, communicating with a base control device, and do not use controllers capable of controlling and communicating among large numbers of robots.
When a distributed search system includes multiple robots such as a fleet of autonomous vehicles, reducing the size and expense of on-board compute resources improves cost effectiveness. One example of a need for cooperating robotic vehicles is in applications where autonomous robotic vehicles are used to locate a scent or a plume source (such as a bomb target, chemical source, temperature or radiation source, steam, dry ice, and humidity). Each robotic vehicle with on-board sensors needs to be inexpensive in order to utilize multiple robots in quantity in cooperating searches. An inexpensive system can have a small amount of compute power, a small amount of memory, and on-board sensors.
Lewis et al. discloses the use of a squad of all terrain RATLER(trademark) (roving all terrain lunar explorer rovers) vehicles, like those developed at Sandia National Laboratories, for remote cooperative control and sensing in outdoor perimeter detection applications. See Lewis et al., xe2x80x9cCooperative Control of a Squad of Mobile Vehicles,xe2x80x9d IASTED International Conference on Control and Applications, Honolulu, Hi., Aug. 12-14, 1998. RATLER(trademark) platforms are highly capable but could be cost prohibitive used in large quantity. Lewis et al. teaches perimeter control and squad formation relative to a lead vehicle, with tele-operation by an operator and autonomous navigation to GPS locations with a geographic information system (GIS) map. Lewis et al. does not disclose a miniature mobile robot or teach distributed mobile robots sharing information to update a cooperative search strategy in a system.
Byrne et al; xe2x80x9cDesign of a Miniature Robotic Vehicle,xe2x80x9d Proceedings of the Eighteenth IASTED International Conference, Innsbruck, Austria, pp. 428-430, February 1999, describes a robotic vehicle occupying approximately 0.5 cubic inches with a lithium battery allowing about 10 minutes of operation. The robot has limited mobility due to its small wheels and a limited lifetime due to the small battery. Byrne et al. does not disclose a robotic vehicle having a lifetime long enough to perform source searches.
Small robots are useful for research and education. Examples of small robots available commercially include those manufactured by K-Team. K-alice robot available from K-Team is capable of infrared sensing, light sensing, and motion control. K-alice specifications do not disclose a radio capable of bi-directional communications among multiple robots and a base station. Khepera robot available from K-Team is a larger robot capable of sensing, motion control, and communication. Khepera robot information discloses capabilities for trajectory planning and obstacle avoidance but does not disclose execution capabilities for a source localization controller. See K-Team product information, xe2x80x9cK-alicexe2x80x9d and xe2x80x9cKhepera family,xe2x80x9d April 2001, available from the Internet.
iRobot""s swarm robots utilize a multi-robot operating system and communicate with their neighbors using infrared light. iRobot swarm description discloses capabilities for group positioning into defined shapes but does not disclose execution capabilities for a source localization controller. See iRobot, xe2x80x9cSwarm: Distributed programming of autonomous robots,xe2x80x9d April 2001, accessible over the Internet.
Due to potentially prohibitive costs of robots with their associated sensors and electronics, it is desirable to produce lower cost robots for use in quantity. Interest in the use of multiple robots in the previously mentioned application areas is growing due to recent technical and cost advances in microelectronics and sensors. These advances include small, low power CCD cameras; small microprocessors with expanded capabilities; autonomous navigation systems using global positioning systems; and several types of small sensors.
There is a need for cooperative system using inexpensive, easy to fabricate, autonomous vehicles, capable of being built in quantity, that can be used in conjunction with advances in microelectronics and sensors. These robotic vehicles need to have sufficient power to be capable of performing searches and be capable of providing communications for cooperating with other robots in source searches. Accordingly, there is an unmet need for a system using cooperating mobile robots suitable for providing independent and distributed sensing and sharing of information as well as cooperative control for each robot to improve its search strategy to achieve an objective using a distributed search system.
Cooperative System
Multiple agents or processors in a collective can collect and share information using a cooperative search controller to make better decisions in order to achieve the objective. One example of a cooperative search controller for testing with the present invention uses distributed robot sensors and cooperative control approach to effectively control multiple autonomous, robotic vehicles to locate a source within a test area.
Hurtado et al. teaches a method to control a large swarm of autonomous robotic vehicles performing a search and tag operation. See Hurtado et al., xe2x80x9cDistributed Sensing and Cooperative Control for Swarms of Robotic Vehicles,xe2x80x9d Proceedings of IASTED International Conference on Control and Applications, Honolulu, Hi., Aug. 12-14, 1998, pp. 175-178. Hurtado et al. simulates agents with distributed sensing and information sharing for cooperative approximation of the location of a search source. Hurtado et at. does not disclose a miniature mobile robot or disclose a system of miniature mobile robots for testing a cooperative search controller.
Search controllers also need to be tested and experimentally verified. A controller intended to be used on mid- to large-scale robots can be expensive to test on those larger-scale platforms in a real-world environment. The use of smaller, less expensive robots in a smaller-scale test environment can provide experimental results using a larger number of robots to more effectively test the search controllers. A particular example environment is a search and tag operation to find the source of a time-varying chemical plume, temperature source, radiation source, or light source.
There is a need to be able to test a controller on multiple robots in a test environment where the efficacy and robustness of the controller can be evaluated without undue cost, using multiple robots that are relatively inexpensive to fabricate, capable of being built in quantity, and that can be used in conjunction with advances in microelectronics and sensors.
The present invention provides a cooperative system using mobile robots for testing a source localization controller to locate a source in a test area. The system further comprises a source generator for generating the source. The system further comprises a camera system, capable of observing the robots in the test area, and interfacing with a base station in communication with each robot.
The present invention teaches a method for testing a cooperative search controller, using a test system comprising a tracking device and multiple mobile robots cooperating to locate a source in a test area, with each robot comprising a sensor, a processor, a memory, and a communication device. Communications, processor, and memory are capable of executing source localization controller software using a reconfigurable network.